Count particular key value from array of object

Question

I have following JSON array I want to create object form status key count

[
  {
    "id": "65:0",    
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "RED"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
   {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  }
]

Want to count status key value and create the following Object

{
 'ORANGE' : 3,
 'GREEN' : 4,
 'YELLOW' : 2,
 'RED' : 1,
}

FYI, use `array.filter`, `array.map`, `array.reduce`, etc. They will help loads. — evolutionxbox, Aug 01 '16 at 09:13
This may also help http://stackoverflow.com/questions/24252305/using-array-reduce-method-to-count-duplicate-elements — evolutionxbox, Aug 01 '16 at 09:17
Please help me on this https://stackoverflow.com/questions/72084738/count-object-based-on-status-and-shop-using-javascript — its me, May 02 '22 at 09:38

Pranav C Balan · Accepted Answer · 2016-08-01T09:24:04.853

30

Use Array#reduce method

var res = data.reduce(function(obj, v) {
  // increment or set the property
  // `(obj[v.status] || 0)` returns the property value if defined
  // or 0 ( since `undefined` is a falsy value
  obj[v.status] = (obj[v.status] || 0) + 1;
  // return the updated object
  return obj;
  // set the initial value as an object
}, {})

var data = [{
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "RED"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "GREEN"
}];

var res = data.reduce(function(obj, v) {
  obj[v.status] = (obj[v.status] || 0) + 1;
  return obj;
}, {})

console.log(res);

Although you can use Array#forEach method with the same code.

var res = {};
data.forEach(function(v) {
  res[v.status] = (res[v.status] || 0) + 1;
})

var data = [{
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "RED"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "GREEN"
}, {
  "id": "65:0",
  "status": "ORANGE"
}, {
  "id": "65:0",
  "status": "YELLOW"
}, {
  "id": "65:0",
  "status": "GREEN"
}];

var res = {};
data.forEach(function(v) {
  res[v.status] = (res[v.status] || 0) + 1;
})

console.log(res);

edited Aug 01 '16 at 09:24

answered Aug 01 '16 at 09:16

Pranav C Balan

113,687
23
165
188

could you tell me how to push the output to object array so we can use it later (in your Array#forEach method )?Thanks – user1788736 Mar 23 '19 at 13:27
@user1788736 : what you mean by object array... something like `[{...},{...},....]` – Pranav C Balan Mar 23 '19 at 13:31
Thanks for your quick reply. Yes like this [{statusType:"orange",statusSize:3},{statusType:"green",statusSize:4},{..}..]. I tried this inside for each loop but it did not store those information MyObjectArray.push({ statusType: res[v.status], statusSize: (res[v.status] || 0) + 1 }); – user1788736 Mar 23 '19 at 13:41
@user1788736 : share your data – Pranav C Balan Mar 23 '19 at 13:43
var MyObjectArray = [ {userId:"10",userName:"david",displayUrl:"https://www.somesite.com/1david.jpg"}, {userId:"12",userName:"edward",displayUrl:"https://www.somesite.com/1edward.jpg"}, {userId:"10",userName:"david",displayUrl:"https://www.somesite.com/2david.jpg"}, {userId:"12",userName:"edward",displayUrl:"https://www.somesite.com/2edward.jpg"}, {userId:"10",userName:"david",displayUrl:"https://www.somesite.com/3david.jpg"} ]; and i want to push this info to another object array: var MyNewObjectArray =[ {userId:10,repeatedTimes:3},{userId:12,repeatedTimes:2}] – user1788736 Mar 23 '19 at 13:53
@user1788736 `let ref = {}; let res = []; data.forEach(function(o) { if (!(o.userId in ref)) res[ref[o.userId] = res.length] = { userId: o.userId, repeatedTimes: 0 } res[ref[o.userId]].repeatedTimes++; }) console.log(res);` – Pranav C Balan Mar 23 '19 at 14:07
can i use var instead of let for decaring the object arrays ? i want to be able to use them in other functions as well? – user1788736 Mar 23 '19 at 18:50
@user1788736 : yeah sure u can – Pranav C Balan Mar 23 '19 at 18:58
Please help me on this https://stackoverflow.com/questions/72084738/count-object-based-on-status-and-shop-using-javascript – its me May 02 '22 at 09:39

Vladu Ionut · Answer 2 · 2016-08-01T09:26:14.207

var obj = [
  {
    "id": "65:0",    
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "name": "BIU",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "name": "BIU",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "RED"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
   {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  }
] ;

var rez={};
obj.forEach(function(item){
  rez[item.status] ? rez[item.status]++ :  rez[item.status] = 1;
});
console.log(rez);

varsha ghodki · Answer 3 · 2016-08-01T09:45:53.350

1

Do you want this output format?

var json=[
  {
    "id": "65:0",    
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "RED"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  },
   {
    "id": "65:0",
    "status": "ORANGE"
  },
  {
    "id": "65:0",
    "status": "YELLOW"
  },
  {
    "id": "65:0",
    "status": "GREEN"
  }
] ;

var obj={};
json.forEach(function(item){
obj[item.status]? obj[item.status]++ : obj[item.status]=1;
});

console.log(obj)

edited Aug 01 '16 at 09:45

answered Aug 01 '16 at 09:23

varsha ghodki

201
1
7

Nice way, but only works if it's in sorted order(sorted based on `status` property).. specify that in your answer... – Pranav C Balan Aug 01 '16 at 09:33
1

yeh, I can not use index over there. I updated my code:P. – varsha ghodki Aug 01 '16 at 09:48

Count particular key value from array of object

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